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May ❘ June 2005 IT Pro 271520-9202/05/$20.00 © 2005 IEEE P u b l i s h e d b y t h e I E E E C o m p u t e r S o c i e t y

RFID: A Technical

Overview andIts Application tothe Enterprise

Ron Weinstein

R

adio frequency identification (RFID)has been around for decades. Onlyrecently,however,has the convergence

of lower cost and increased capabilitiesmade businesses take a hard look at what RFIDcan do for them.A major push came when retail-ing giant Wal-Mart dramatically announced thatit would require its top 100 suppliers to supplyRFID-enabled shipments by January 2005.Though the bottom line story of that deploymenthas yet to surface, it does seem to support theinevitable movement of inventory tracking andsupply chain management toward RFID.

This article offers an RFID tutorial thatanswers the following questions:

• What is RFID, and how does it work?• What are some applications of RFID?• What are some challenges and problems in

RFID technology and implementation?• How have some organizations implemented

RFID?

Answering these ques-tions will provide anorganizational frame-work for RFID imple-mentation from both the

technical and businessperspectives.

TECHNICAL OVERVIEWThe basic premise behind RFID systems is that

you mark items with tags. These tags contain

transponders that emit messages readable by spe-cialized RFID readers. Most RFID tags storesome sort of identification number;for example acustomer number or product SKU (stock-keep-ing unit) code. A reader retrieves informationabout the ID number from a database, and actsupon it accordingly. RFID tags can also containwritable memory,which can store information fortransfer to various RFID readers in different loca-tions.This information can track the movementof the tagged item,making that information avail-able to each reader (“A Guide to UnderstandingRFID,” RFID J., retrieved 27 Feb. 2005; http://www.rfidjournal.com/article/gettingstarted/).

RFID tags fall into two general categories,active and passive, depending on their source of electrical power.Active RFID tags contain theirown power source, usually an on-board battery.Passive tags obtain power from the signal of anexternal reader.RFID readers also come in activeand passive varieties, depending on the type of tag they read.

Active tagsBecause they have their own power source,

active tags transmit a stronger signal,and readerscan access them from further away.The on-board

RFID offers tantalizing benefits for

supply chain management, inventory

control, and many other applications.

Find out whether your companycould benefit.

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28 IT Pro May ❘ June 2005

N E W T E C H N O L O G Y

power source makes them larger and more expensive, soactive RFID systems typically work best on large itemstracked over long distances. Low-power active tags areusually slightly larger than a deck of playing cards.Active

tags can remain dormant until they come in range of areceiver or can constantly broadcast a signal.

Because of their on-board power source,active tags oper-ate at higher frequencies—commonly 455 MHz,2.45 GHz,or 5.8 GHz—depending on the application’s read rangeand memory requirements.Readers can communicate withactive RFID tags across 20 to 100 meters.

Passive tagsPassive tags, on the other hand, are very inexpensive;

they can cost as little as 20 cents apiece, and new tech-nologies are constantly making them cheaper to integrateinto common materials and products. Because passive tagsare inexpensive, they will likely be the basis of most of thegrowth in RFID implementations, so I will examine thetechnology behind passive tags in detail.

In addition to their low cost, passive tags can also bequite small. Current antenna technology limits the small-est useful passive tag to about the size of a quarter. Thelarger the tag, the larger the read range.

Currently, passive RFID tags contain about 2 Kbits of memory. This is too small to hold much more complexinformation than identification and history information.The technology behind RFID is constantly improving, sothe amount of information and capabilities of RFID tags

will increase over time,allowing RFID tags to eventuallycontain and transmit much more information.

A passive-tag reader canconstantly broadcast its signal

or broadcast it on demand.When a tag comes within thereader’s range, it receives anelectromagnetic signal fromthe reader through the tag’santenna. The tag then storesthe energy from the signalin an on-board capacitor, aprocess called inductive cou- pling.When the capacitor hasbuilt up enough charge, it canpower the RFID tag’s cir-cuitry, which transmits a mod-

ulated signal to the reader.That return signal containsthe information stored in thetag.

The communication be-tween the reader and passivetag uses one of two methodsto modulate the ID signal.Low-frequency (less than 100

MHz) tags pass information by releasing energy from thecapacitor to the tag coils in varying strengths over time,which affects the radio frequency emitted by the tag. Thereader detects these varying waves and can use these vari-

ances to demodulate the code. Figure 1 shows this loadmodulation.

In higher-frequency (greater than 100 MHz) tags, the tagtransmits the signal using backscatter , in which the tag’scircuit changes the resistance of the tag’s antenna.Thischange in resistance causes a transmission of RF waves,which the reader can pick up and demodulate.Passive tagstypically operate at frequencies of 128 KHz,13.6 MHz,915MHz, or 2.45 GHz, and have read ranges of a few inchesto 30 feet. Frequency choice depends on the system’s envi-ronment,what material the signal must travel through,andthe system’s required read range.

RFID tags can be encased in many materials.Plastics area very common material for RFID, forming identificationcards for building access,credit cards,or bus fares.Tags canalso go on the back of labels printed on standard ink jetprinters, for placement on inventory.

STANDARDSSeveral RFID standards exist, and their applications are

under debate within the RFID development community.These standards cover

• identification, the coding of unique item identifiers, orother data on the RF tag;

• data and system protocols, effectively the middlewareof an RFID system;

Passive RFID tag

RFIDreader

1. RFID readerbroadcasts

electromagneticsignal to tag.

2. Antenna in the tagreceives the signal

from the reader andstores charge in

a capacitor.

3. When thecapacitor has

built upenough energy, it

releases it overtime to thetag’s coils.

4. The tag’s coils release an encoded radiowave containing the information in the tag,

which the reader then demodulates.

Figure 1. Simplified view of data transfer in

low-frequency passive RFID tags (the tag isenlarged for clarity).


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• the air interface, that is, the wireless com-munication between the reader and the tag;

• application support, which provides adviceabout how to implement the technology;• testing, compliance, and health and safety,

that is, the rules that govern RFID opera-tions; and

• terminology.

The International StandardsOrganization (ISO) has threestandards for RFID: ISO14443 (for contactless sys-tems), ISO 15693 (for vicinitysystems, such as ID badges),

and ISO 18000 (to specify theair interface for a variety of RFID applica-tions). A not-for-profit organization,EPCglobal, has developed a widely acceptedstandard for product identification. TheElectronic Product Code (EPC) standard cov-ers the air interfaces, the format for the prod-uct identification data stored in an RFID tag,and the middleware and databases storinginformation about the tags.

The US Department of Defense nowrequires suppliers to use RFID “on lowestpossible piece part/case/pallet packaging once

the supplier’s contract contains languageregarding the requirement” (http://www.dodrfid.org).The DoD specifies EPCglobal orcompatible tags. In 2004, the DoD ran a fieldtest RFID deployment, as the “US NavyRFID Pilot” sidebar describes.

EPCglobal has developed a system called the ObjectNaming Service (ONS) that is similar to the Domain NameService (DNS) used on the Internet. ONS acts as a direc-tory service for organizations wishing to look up productnumbers (also known as EPC numbers) on the Internet.EPCglobal awarded VeriSign a contract to manage ONSin January 2004.(“VeriSign to Run EPC Directory,”RFID J., 13 Jan. 2004; http://www.rfidjournal.com/article/view/735/). In reports dated January, 2004, Wal-Mart, though amember company of EPCglobal, reported that it has noplans to use the ONS service, opting to use its own pro-prietary database and formats.

In terms of the all important air interface,ISO 18000 andthe EPC standard were incompatible.However, in January2005, EPCglobal submitted its UHF Class 1 Generation 2Specification for possible inclusion in the ISO standards.The National RFID Centre, an initiative of the UKDepartment of Trade and Industry, hailed the move as amuch needed convergence of international RFID stan-

dards (“Convergence of RFID Standardisation Efforts,”13 Jan.2005,http://www.rfiduk.org/news/view. php?id=3).

In May 2004, the US Navy finished its pilot of a passive-RFIDsystem to support the loading of supplies into cargo containers.The pilot project took place at the Fleet and Industrial Supply

Center (FISC) in Norfolk, Virginia; the originalgoal was to reduce the number of errors in recordsof supplies loaded into the containers.These errorsarose from manual and/or nominally automateddata inputs in the standing process. For the pilot,FISC used passive tags read as a forklift carryingthe supplies (shipments) passed through speciallyequipped portals. In all, FISC spent $306,000, or93 cents per shipment during this pilot.

In its final configuration, the RFID-enhanced process alsoincreased the speed and efficiency of the cargo checking process.Although the pilot’s goal did not include a return-on-investment justification,the final report indicates that “as many as twelve addi-tional personnel could conceptually be assigned as additional driv-ers, or to work in other functions within the operation” becausemonitoring the RFID pilot system did not require as many peopleas the legacy system.In the process,FISC learned several valuablelessons that would apply to similar RFID deployments.The report Final Report of the Passive Radio-Frequency Identification(RFID) Project at the Fleet and Industrial Supply Center,

Norfolk, Virginia, Ocean Terminal describes those lessons andthe pilot project in detail (http://www.acq.osd.mil/log/logistics_materiel_readiness/organizations/sci/rfid/assetts/Meetings/FISC%20Norfolk%20OT%20Report%20v8.pdf).

US Navy RFID Pilot

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BUSINESS APPLICATIONSRFID applications are numerous and far reaching.The

most interesting and widely used applications includethose for supply chain management,security,and the track-

ing of important objects and personnel.

Supply chain managementIn supply chain management, RFID tags are used to

track products throughout the supply chain—from sup-plier delivery, to warehouse stock and point of sale. Newapplications target tracking from checkout through cus-tomer billing. A central database records product move-ment,which manufacturers or retailers can later query forlocation, delivery confirmation, or theft prevention.

For this application,RFID basically serves as a replace-ment for the bar code scanners used to track products andshipments in similar ways. Gao and colleagues outlinesfour ways in which RFID is superior to bar codes for track-ing inventory flow over the supply chain (“An Approachto Security and Privacy of RFID System for SupplyChain,” X. Gao and colleagues, Proc. IEEE Int’l Conf.E-Commerce Technology for Dynamic E-Business,2004):

• RFID does not require line-of-sight access to read thetag.

• The read range of RFID is larger than that of a bar codereader.

• Readers can simultaneously communicate with multi-ple RFID tags. Because of this capability, an RFID

reader can capture the contents of an entire shipmentas it is loaded into a warehouse or shipping container.

A reader collects detail information in one pass, with-out having to scan each product.

• Tags can store more data than bar codes.

The last capability has several interesting applicationsin supply chain management.For example, read-write tagscan store information about their environment.They canphysically store their position and time throughout theirmovement in the supply chain.

An example of a proposed use of RFID is to ensure safetyin the supply chain. A US Food and Drug Administration(FDA) proposal supports using RFID to ensure the authen-ticity of prescription drugs. In this system,each drug ship-ment would carry a read-only RFID tag containing aunique serial number. Suppliers would track these serial

numbers in shipment and have the drug purchaser verifythe numbers on receipt,ensuring that the drugs came fromwhere they were expected and arrived at their intendedpoint of sale.The FDA realized that this is rather difficultto implement in such a large and supply chain as that forprescription drugs and proposed a three-year schedule forinvestigating the technology, ending in 2007,before it setsany policies (Combating Counterfeit Drugs, US Food andDrug Administration,Feb.2004;http://www.fda.gov/oc/ini-tiatives/counterfeit/report02_04.html#radiofrequency).

A correlation to the supply chain management applica-tion is to enable automated just-in-time product shipments.If all products in a retail store and associated warehouses

have RFID tags, a store should have an accurate databaseof its inventory.Systems in retail outlets could automaticallyalert a warehouse management system that inventories arelow.The warehouse management system could locate theproducts in the warehouse based on their initial scan, andautomatically move them to a loading dock for shipping tothe retail outlet.Wal-Mart is implementing such a system.

SecuritySecurity and personal identification applications are a

major and broad application of RFID.A common use of RFID is in identification cards to control building access.Many organizations use RFID tags embedded in ID cards,which are readable at a building entrance.

On a similar note,some credit cards (American Express’ExpressPay,http://www.americanexpress.com/expresspay)and other payment devices, such as ExxonMobil’s Speed-pass (http://www.speedpass.com), use RFID tags. Othercards use tags for automatic fare payment in mass-transitsystems,such as the SmarTrip card for the Washington DCarea subway and bus system (http://www.wmata.com/riding/smartrip.cfm). Figure 2 shows samples of such cards.Essentially,these are a replacement for identification cardswith magnetic stripes, providing a more reliable way tostore identification information—magnetic stripes tend to

wear out and lose information over time. RFID tags alsohave a higher memory capacity than magnetic stripes.

Figure 2. Common devices that

employ RFID.

Some car keys (upper left) contain a passive tag.AnEzPass (upper right) helps collect highway tolls,a SmarTrip card (bottom) collects fares in a publictransit system.


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May ❘ June 2005 IT Pro 31

Keys for new cars also incorporate passiveRFID tags that work with a reader near the

car’s ignition switch.The reader will only acceptcodes stored in certain keys. If the code in a keydoes not match the reader in the car, the car willnot start, making it more difficult to steal vehi-cles by copying keys.

Movement trackingBecause moving objects can easily carry

RFID tags,a common use is to track the move-ment of people and the information associatedwith them. Some hospitals now use tags on new-borns, to ensure identification and to alert hos-pital staff should someone attempt to take the

baby outside of the hospital without authoriza-tion. Some schools are requiring children towear tag-embedded bracelets or wrist bandswhile on school grounds,to monitor attendanceand to locate lost children (“Tagging Toddlersand Toothpaste,” Information Management J.,Sept.-Oct.2004).The FDA recently approved aRFID tag that could stay with surgical patientsin hospitals and store information on the surgi-cal procedure the person requires, eliminatingsurprisingly common surgical mistakes (“FDAApproves Surgical ID Tag,”S.Lawrence, eWeek,Nov.2004;http://www.eweek.com/article2/0,1759,1731402,00.asp).

This application of RFID has obvious privacy issues, as Iwill discuss later.

In the same way, tags can track the movement of highlymobile objects in areas other than an organization’s sup-ply chain. For example, one large Las Vegas casino plansto place passive tags in each gaming chip, and have read-ers at cashier stations and gaming tables. In this way, thecasino can detect counterfeit chips, and track the move-ment of chips and player activity (“Vegas Casino Betson RFID,” A. Gilbert, 9 Feb. 2005, http://news.com.com/Vegas+casino+bets+on+RFID/2100-7355_3-5568288.html?tag=nefd.top).

Hospitals are also using RFID to track equipmentthroughout a facility as it moves from room to room. Thishelps manage inventory and ensure the proper mainte-nance of equipment. Libraries also tag books, making itpossible to easily locate a book in the stacks, prevent theft,and automate the checkout process.

CHALLENGES AND ISSUES IN RFIDAlthough promising,RFID is not without its challenges,

which arise from both a technological and usage point of view.

Privacy concerns

A common concern with RFID is privacy. It is discon-certing for many people to have their movements or buy-

ing habits automatically tracked electronically. Many pri-vacy groups are concerned about the ability to identify

people as they walk through a store or shopping center viathe tags embedded in their clothing and linked to them atthe time of purchase.

To counter such concerns, RFID proponents proposethat retail tags have “kill switches” that disable the tag atthe point of sale. Even though a small tag might remainembedded inside a product, once the kill switch is acti-vated, the tag would no longer transmit information(“Some Methods for Privacy in RFID Communication,” R.Fishkin and B. Jiang, Intel Research; http:// www.intel-research.net/Publications/Seattle/062420041517_243.pdf).

Many of the privacy concerns regarding RFID areaddressable because of the nature of RFID tags them-selves.The read range of RFID tags is much too small toallow readers out of personal range to read tags carried ona person or in a vehicle.Also, building materials tend toabsorb the relatively weak RF waves transmitted by pas-sive tags,making it extremely difficult to pick up RFID sig-nals through the walls of a home (“RFID PrivacyWorkshop: Concerns,Consensus,and Questions,”S.Weiss, IEEE Security & Privacy, Mar.-Apr. 2004).

However, anytime someone automatically stores andtracks personal identification in electronic databases, pri-vacy concerns are very real. RFID tags used in trans-

portation systems—whether for fare collection on masstransit systems or automatic toll payment on bridges and

➤ Association for Automatic Identification and Mobility (AIM,http://www.aimglobal.org/technologies/rfid):A trade associ-ation, AIM focuses on automatic identification; its siteincludes a buyer’s guide to RFID hardware and a solutionprovider evaluation guide.

➤ RFID Gazette (http://www.rfidgazette.org): A blog, theGazette reviews RFID products and implementations.

➤ Sybase RFID Platform (http://www.sybase.com/rfid): Anexample RFID middleware implementation.

➤ The RFID Handbook (http://rfid-handbook.com):The home

page for the book contains links to many companies provid-ing RFID products and solutions.

Tutorials➤ “A Guide to Understanding RFID,” RFID J.; http://www.

rfidjournal.com/article/gettingstarted/.➤ “RFID 101,” W. Singer, Logistics Today, Nov. 2004.➤ “The Magic of RFID,” R. Want, ACM Queue, Oct. 2004.

Resources for

RFID Products


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highways—allows for the easy and unprecedented track-ing of movement. If you can pay for products in an RFID

tag and companies later bill you automatically, it takes allpossible anonymity out of the retail process. Companiesand government agencies must address these concernsbefore the public will truly feel comfortable using RFIDsystems. People will want to see policies about the use of an RFID system and the information it collects.

SecuritySecurity is another key issue in RFID. An organization

that implements RFID in its supply chain does not wantcompetitors to track its shipments and inventory. Peoplewho use devices that carry personal financial information,such as credit card or other ID numbers,do not want oth-

ers to access their accounts.These are significant securityvulnerabilities in RFID.

Some researchers have proposed schemes that wouldrequire tags to authenticate readers, transmitting infor-mation only to authorized readers.The tags would have tostore ID numbers for authorized readers, and a readerwould have to broadcast its ID to the tag. To protect thereader’s ID—and prevent others from eavesdropping andstealing the information—the reader uses either a fixed orrandomly generated number to hash (encrypt) its ID (Gaoand colleagues).

If the tag cannot authenticate the reader’s identity, thetag will refuse to transmit the information it stores. Like

most security tactics, this scheme is vulnerable to attacks,such as man in the middle,or reverse engineering.

Integration with legacy systemsAnother challenge to RFID is its integration into exist-

ing systems. Several vendors are developing RFID mid-dleware that will link new RFID systems into existingback-end infrastructures. Middleware, for example, canhelp with the current lack of standards in RFID. If anorganization picks a standard that changes or loses its mar-ket prevalence, middleware can transform the data fromreaders into the format supported by back-end systems.Many RFID middleware systems provide hooks into oper-

ational monitors,so organizations can monitor their taggeditems in real time (“RFID Anywhere: Leapfrogging theChallenges of RFID Deployment,” Sybase Inc.; http://sybase.com/detail?id=1034549). Middleware can providethe primary link between RFID readers and databases.

WAL-MART: TAKING THE LEADIN RFID FOR RETAIL

Of the many organizations having implemented RFID,the one that received the most media attention is Wal-Mart.The world’s largest retailer,Wal-Mart has one of the most

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efficient supply chains in the world.With a large array of suppliers from many different industries,Wal-Mart’s RFID

effort has the potential to cause a web of RFID implemen-tations. One estimate puts Wal-Mart’s savings at $8.35 bil-lion per year if it fully implemented RFID throughout itsoperations.That figure is more than the total revenue of half the companies on the Fortune 500 (“Case Study:Wal-Mart’sRace for RFID,” M. Roberti, eWeek, Sept. 2003;http://www.eweek.com/article2/0,1759,1492297, 00.asp).

Though this savings is substantial,Wal-Mart has takenits RFID implementation fairly slowly. In 11 June 2003,Wal-Mart announced that it would require its top 100 sup-pliers to tag all cases and pallets by January 2005. Thisdirective sent a wave of panic among suppliers, who scur-ried to learn about RFID and how best to implement the

technology.Wal-Mart and its suppliers quickly found several chal-

lenges in its RFID implementation,namely that the UHFfrequency they were using as a standard would not passthrough many common products shipped to retail stores,such as water-based products and products shipped inmetal packaging.This forced Wal-Mart to back off slightlyand relax its deadline for full RFID implementation. ByJanuary 2005,the top 100 suppliers had only tagged about60 percent of their products. Wal-Mart, though, was thefirst major retailer to implement RFID throughout thesupply chain,and force its suppliers to implement RFID aswell, so it’s natural to have some problems.Wal-Mart’s

early adopter implementation forced the industry to learnabout the challenges in RFID (“Wal-Mart Gives SuppliersRFID Holiday Gift, E. Schuman, eWeek, Dec. 2004;http://www.eweek.com/article2/0,1759,1744834,00.asp).

Wal-Mart provides information about its RFID effortsat http://www.walmartstores.com/wmstore/wmstores/Mainsupplier.jsp?pagetype=supplier&categoryOID=10605&catID=-8250&template=DisplayAllContents.jsp.

RFID, a technology existing for years, has potentialuses in a variety of applications.Though not withoutissues and challenges, RFID is a promising technol-

ogy which analysts expect to become ubiquitous in thecoming years,helping organizations solve problems in sup-ply chain management, security, personal identification,and asset tracking.■

Ron Weinstein is a graduate student at Johns Hopkins Uni-versity. He also works for Sybase as a consultant. Contact

him at [email protected]

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